1. Field of the Invention
The present invention relates to a sheet-fed scanner, and more particularly, to a sheet-fed scanner with a preview function.
2. Description of the Prior Art
Flatbed scanners are commonly used for scanning document images into computers. Most flatbed scanners can scan documents in high resolution, such as 600.times.600 dpi or more. However, scanning a complete document in high resolution takes a long time and generates a huge amount of image data. Flatbed scanners usually provide a preview function which can quickly scan a document in low resolution to generate a preview image. A user can then specify one or more target areas on the preview image to instruct the scanner to scan only the designated areas, and the scanner will later on scan the designated areas in high resolution and transmit only the images from the designated areas back to a computer. Such preview function greatly reduces the amount of image data and the elapsed time for scanning a document.
However, prior art sheet-fed scanners can not perform such preview function. Sheet-fed scanners currently available in the market are very compact in size and they are designed to scan a document in one pass and then the document is ejected from the sheet-fed scanner completely. Since the document can not be held inside the sheet-fed scanner, there is no way to perform the above mentioned preview function.